For issues related to Microsoft Authenticator (MFA)  such as repeated verification requests, sign in loops, or authentication failures or lost phone.

"I just got a new phone and still have my old one, How can I transfer Microsoft Authenticator to my new phone?"

If you get a new phone and still have access to your old phone, log into: My Sign-Ins | Security Info | Microsoft.com 

• Delete the current Microsoft Authenticator sign-in method
• Click on "Add Sign-In Method" and select "Authenticator app" in the drop-down menu 
• Download the Microsoft Authenticator App on your smartphone
• Follow along the setup wizard